1. Field of the Invention
The present invention relates to transceivers and IC packages. More specifically, the present invention relates to transceivers that can be directly plugged into an IC package.
2. Description of the Related Art
FIG. 18 shows a conventional transceiver 500 and a conventional integrated circuit (IC) package 504. The transceiver 500 is connected to a socket 501 on a printed circuit board (PCB) 503. The IC package 504 is connected to the PCB 503 through solder balls 504a. The IC package 504 is a ball grid array (BGA). The IC package 504 is connected to the socket 501 by traces 502 located on or in the PCB 503. The transceiver 500 includes an optical engine that provides optical-to-electrical and electrical-to-optical conversion. That is, the electrical signals received from the IC package 504 are converted to optical signals that are transmitted through the optical fiber cable 500a, and all optical signals received through the optical fiber cable 500a are converted to electrical signals and are transmitted to the IC package 504 through the traces 502 on the PCB 503 and the solder balls 504a. 
Increased bandwidth demands make it difficult to transmit data to and from IC packages over copper connections, including the traces 502 shown in FIG. 18. Signals to and from the IC package have to travel over a long distance. For example, an electrical signal transmitted by an IC die (not shown in FIG. 18) of the IC package 504 has to be transmitted through an IC circuit board (not shown in FIG. 18), through solder balls 504a, along traces 504 on the PCB 503 to the socket 501, and finally to the transceiver 500 where the electrical signals are converted to optical signals and transmitted through the optical fiber cable 500a. Optical signals transmitted from the optical fiber cable 500a to the transceiver 500 must follow the same lengthy path, but in reverse. The length of this path can reach up to 20 inches. High-end applications, such as switches, can use many transceivers, in which the optical and electrical signals for each of the transceivers must travel similarly lengthy paths. This approach as shown in FIG. 18 with a lengthy path has many drawbacks, including:                1. Requiring more power to amplify or recover the data signals, which increases the bit error rate and which creates some limitations in the placements of components on the PCB, because data signals have to travel over lossy copper traces on a PCB.        2. Increasing costs by increasing the number of components, including connectors, transceiver cages, housing, etc. and requiring a larger number of BGA connections between the IC package and the PCB because all the data signals have to be transmitted to and from the BGA of the IC package.        
Known transceivers, including the conventional transceiver 500 shown in FIG. 18, cannot be adapted for connecting directly to an IC package because known transceivers are not small enough or have adequate mechanical retention. Known transceivers require a large amount of space and consume hardware to mate or dock the optical engine. Known transceivers cannot be adapted to both on-board and ball grid array (BGA) stepped-plane environments. Size and geometry of known transceivers is limited by interference from low-speed signals and power signals being carried in the same transceiver as the high-speed signals.
Known LGA connector systems require additional hardware to mate and operate, including, for example, springs, fasteners, latch bars or levers, latches for heat sinks. This hardware applies even compression pressure over the top of connector systems. Springs are typically used to allow for thermal expansion while applying and distributing force. Added hardware is typically used for alignment and ease of installation for electrical, optical alignment, and mechanical reasons.
FIG. 19A shows a known IC package 514 that includes a socket 510 that includes a multi-fiber push-on (MPO) 511. The IC package 514 also includes an IC die 515 and a circuit board 516 with solder balls 516a. MPO 511 is an optical connector in which optical signals are inputted and outputted. All the optical components, including those that convert optical signals to electrical signals and convert electrical signals to optical signals, must be located in the IC package 514 and cannot be easily replaced if they fail. That is, the IC package 514 must include, in addition to MPO 511, a converter that converts optical signals to electrical signals and that converts electrical signals to optical signals, which increases the size and cost of the IC package 514. Because the converter must be included in the IC package 514 when it is manufactured, the converter must also be able to tolerate the reflow temperatures used when the IC package 514 is connected to host circuit board (not shown in FIGS. 19A and 19B). Further, the IC package fails if either the IC die 515 or the converter fails. FIG. 19B shows a conventional modification of the IC package 514 shown in FIG. 19A in which the conventional IC package 524 includes a socket 520 located on the opposite side of the IC package 524 as the MPO 521. The socket 520 and the MPO 521 are connected by fiber optic cables 527. The IC package 524 includes an IC die 525 and a circuit board 526 with solder balls 526a. Because MPO 511 is an optical connector, MPO 511 is more expensive than a copper connector, and is sensitive to dust and other contamination. MPO 511 also requires expensive precision mechanical latching to ensure proper alignment of the optical connector that mates with the MPO 511. The mechanical latching causes the MPO 511 to be sensitive to mechanical stress on the fibers connected to the MPO 511, which can create optical misalignment. The IC package 514 requires more stringent stiffness requirements compared to IC packages that can be used with copper connectors. In addition, the IC package 514 cannot be tested electrically during production because only a very expensive optical tester can be used.
Known transceivers, which typically include an optical engine and typically use pluggable connectors, are not designed to be directly connected to an IC package. Known transceivers are not small enough or have adequate mechanical retention. Known transceivers require a large amount of space and require hardware to mate or dock the optical engine. Known transceivers cannot be adapted to both on-board and ball grid array (BGA) stepped-plane environments.
Typical transceivers have a single electrical connector that transmits all of the high speed signals, the low speed signals, and the power and ground signals, which limits miniaturization of the transceiver. Known IC package connector systems require additional hardware to mate and operate, including, for example, springs, fasteners, latch bars or levers, latches for heat sinks. This hardware applies even compression pressure over the top of the connector systems. Springs are typically used to allow for thermal expansion while applying and distributing force. Added hardware is typically used for alignment and ease of installation for electrical, optical alignment, and mechanical reasons.